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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 22, Issue 6 - Dec 2008
Volume 22, Issue 5 - Oct 2008
Volume 22, Issue 4 - Aug 2008
Volume 22, Issue 3 - Jun 2008
Volume 22, Issue 2 - Apr 2008
Volume 22, Issue 1 - Feb 2008
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Uplift Capacity of a Plate Anchor Considering Suction Effects
Seo, Young-Kyo ; Kim, Tae-Hyung ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 1~6
Anchors have been commonly used to as foundation systems of the structures that require the uplift resistance. Recently anchors have been used in ocean sediment for mooring systems to stabilizeoffshore structures. In the saturated clayey soil however suction developed between the soil and andchor and affects the uplift capacity of anchor. To estimate the uplift capacity of the andchor accurately, the failure mechanisms of the andchor by the uplift force should also be correctly assumed. The uplift capacity is usually expressed in terms of breakout factors with respect to embedment ratio. In this paper, a two-dimensional plane strain numerical investigation into the vertical uplift capacity of a plate andchor in a clayey soil is described. The breakout factor against their corresponding values of embedment ratio was calculated and plotted along a single curve. The modes of failure mechanism at shallow and deep andchors are also presented.
Effect of the Shape of Absorbing Revetment on Wave Overtopping Rate
Hur, Dong-Soo ; Choi, Dong-Seok ; Choi, Sun-Ho ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 7~12
The present study numerically investigates the effect of the shape of absorbing revetment on wave overtopping rate under regular and irregular incident waves. At first, the numerical model developed by Hur and Choi(2008), which considers the flow through a porous medium with inertial, laminar and turbulent resistance terms, directly simulates Wave-Structure-Sandy seabed interaction and can determine the eddy viscosity with LES turbulent model in 2-Dimensional wave field (LES-WASS-2D), is validated when compared to experimental data. Numerical simulations are then performed to examine the effect of the shape of absorbing revetment and incident wave conditions on wave overtopping rate. The numerical result shows that the wave overtopping rate decreases with the slope gradient of absorbing revetment under both regular and irregular waves. In addition, the effects of mean grain size and porosity of absorbing revetment, incident wave period and crest height on wave overtopping rate are discussed.
Examinations on the Wave Hindcasting of the Abnormal Swells in the East Coast
Kim, Tae-Rim ; Lee, Kang-Ho ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 13~19
Abnormally large swells that appeared on the coast of the East Sea in October in 2005 and 2006 were simulated using SWAN model to examine the accuracy of the model for future forecasting Seawind data calculated based on the weather chart ant bottom topography were used for input data, and the model was operated more than 20 days before the observed swells to avoid the problems from the cold start of the model. The comparisons with observed wind and wave data were unsatisfactory and neededmore improvement in terms of swell component in the wave model as well as the quality of seawind data. The satellite wind and wave data can be good candidates for future comparison of the wave model results in the East Sea.
Estimation of Pollutants Residence Time During the Flood and Dry Season in Gwangyang Bay
Lee, In-Cheol ; Kim, Jin-Hyuk ; Kong, Hwa-Hun ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 20~26
In this paper, in order to set up the management system of water quality environment in Gwangyang Bay, the cluster analysis of water quality environment, the estimation of inflowing pollutant loads and residence time of pollutants in this bay was carried out. The Gwangyang Bay was divided into eight sea areas by cluster analysis and spatio-temporal change of water quality. The river discharges in the Bay were calculated about
from the numerical simulation by Tank model. In addition, inflowing pollutant loads of COD, SS, TN, TP, DIN and DIP in Gwangyang Bay were estimated at 398 ton-COD/day, 2,846 ton-SS/day, 195 ton-TN/day, 5 ton-TP/day, 126 ton-DIN/day and 3 ton-DIP/day, respectively. Moreover, residence times of COD, TN and TP in the Bay was estimated at 6 days-COD, 20 days-TN and 195 days-TP, respectively in the dry season, and 3 days-COD, 6 days-TN and 21 days- TP, respectively, in the flood season. The central part of Gwangyang Bay (Region IV) has the longest residence time of overall pollutants.
Evaluation of Characteristic for SS400 and STS304 Steel by Weld Thermal Cycle Simulation - 3rd Report: Residual Stress and Ultrasonic Parameter
Ahn, Seok-Hwan ; Choi, Moon-Oh ; Jeong, Jeong-Hwan ; Kim, Sung-Kwang ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 27~34
The temperature distribution in the weldment is not uniform because a weldment is locally heated. Thermal plastic deformation results from the local expansion and shrinkage by the heating and cooling of metal. Therefore, residual stresses and distortion occur in the weldment. In this study, we had conducted on the weld thermal cycle simulation that is supposed as the HAZ on SS400 steel and STS304 steel. The residual stresses that were obtained from the drawing and the weld thermal cycle simulation were estimated by X-ray diffraction. We also carried out ultrasonic test for the weld thermal cycle simulated specimens, and then conducted on nondestructive evaluation by the ultrasonic parameters obtained ultrasonic test. From the results, residual stresses of weld thermal cycle simulated specimens after the residual stress removal heat treatment are lower than that of the drawing.
Effect of Counterpart Roughness on Abrasive Wear Characteristics of Side Plate of FRP Ship
Kim, Hyung-Jin ; Koh, Sung-Wi ; Kim, Jae-Dong ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 35~40
The effect of counterpart roughness on abrasive wear characteristics of side plate materials of FRP ship, which were composed of glass fiber and unsaturated polyester resin composites, were investigated at ambient temperature by pin-an-disc friction test. The friction coefficient, wear rate and cumulative wear volume of these materials against SiC abrasive paper were determined experimentally. The wear rate of these materials decreased rapidly with sliding distance and then maintained a constant value. It was increased as counterpart roughness was rougher in a wear test. The cumulative wear volume tended to increase nonlinearly with sliding distance and depended on applied load and sliding speed for these composites. It could be verified by SEM photograph of fracture surface that major failure mechanisms were overlapping layers, microcutting, deformation of resin, delamination, and cracking.
Effects of Carbon Content on the Weldability of B-Containing
Grade High Cr Ferritic Cast Steel for Turbine Casing
Seo, Won-Chan ; Bang, Kook-Soo ; Chi, Byung-Ha ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 41~45
Effectsof carbon content on the weldability of B-containing 620 grade high Cr ferritic cast steels were investigated. Cast steel with lower carbon content of 0.07% showed lower HAZ hardness because of the formation of lower carbon martensite in HAZ. It also showed less solidification cracking susceptibility in weld metal because of the formation of delta ferrite. However, hot ductility showed no difference between cast steels with lower and higher carbon contents. Cast steel with lower carbon content showed greater HAZ softening after PWHT in the region heated between AC1 and AC3 because of its higher base metal hardness.
Development of Alloy with High Strength and Damping Capacity for High-Performance of Precision Devices by Vibration Control
Kana, Chang-Yong ; Kim, Ik-Su ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 46~51
The effect of the addition of Co and N and subzero treatment on tensile strength and damping capacity was investigated in Fe-Cr-Mn alloy. Austenite was transformed into martensite by cold rollins increasing the degree of cold rollins led to an increase in the volume fraction of martensite. The damping capacity linearly increased with increasing volume fraction of
martensite in cold rolled specimens and subzero treated specimens after cold rolling. The volume fraction of
martensite, tensile strength and damping capacity was also increased by the addition of Co, while this treatment decreased the elongation. However, the volume fraction of
martensite, elongation and damping capacity were reduced by the addition of N, although the tensile strength increased. Tensile strength and damping capacity werealso increased by subzero treatment, while elongation decreased.
High Temperature Creep Rupture Characteristics of Ni-Based Alloy718
Kwon, Sang-Woo ; Kong, Yu-Sik ; Kim, Seon-Jin ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 52~57
The short-term high temperature creep rupture behavior of Ni-based Alloy718 steel was investigated at the elevated temperatures range of 550 to
under constant stress conditions. The creep rupture characteristics such as creep stress, rupture time, steady state creep rate, and initial strain were evaluated. Creep stress has a quantitative correlation between creep rupture tim and steady state creep rate. The stress exponents (n, m) of the experimental data at 550, 600, 650 and
were derived as 33.5, -24.9, 26.1, -21.2, 16.8, -12.8 and 10, -8.2, respectively. The stress exponent decreased with increasing creep temperature. The creep lift prediction was derived by the Larson-Miller parameter (LMP) method and the resultant equation was obtained as follows: T(
High Temperature Creep Rupture Characteristics of Ni-Based Alloy718 Jointed by Friction Welding
Kwon, Sang-Woo ; Kong, Yu-Sik ; Kim, Seon-Jin ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 58~63
The short-term high temperature creep rupture behavior of Ni-based Alloy718 steels jointed by friction welding wasinvestigated at the elevated temperatures of 550 to
under constant stress conditions. The creep rupture characteristics such as creep stress, rupture time, steady state creep rate, and initial strain were evaluated. Creep stress has a quantitative correlation between creep rupture time and steady state creep rate. The stress exponents (n, m) of the experimental data at 550, 600, 650 and
were derived as 26.1, -22.4, 22.5, -18.5, 17.4, -14.3 and 6.9, -8.1, respectively. The stress exponents decreased with increasing creep temperature. The creep life prediction was derived by the Larson-Miller parameter (LMP) method and the result equation obtained is as follows: T(logtr+20)=-0.00148
+23232. Finally, the results were compared with those of the base metal for Alloy718.
Numerical Analysis for Hull Cleaning ROV Resistance Performance
Seo, Jang-Hoon ; Yoon, Hyun-Sik ; Chun, Ho-Hwan ; Kim, Su-Hu ; Kim, Tae-Hyung ; Woo, Jong-Sik ; Joo, Young-Sock ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 64~74
The flaw around a ROV (Remotely Operated Vehicle) has been numerically investigated to improve resistance performance by modifying the hull form of the ROV. For the base hull form considered in this study, the form drag rather than the friction drag is dominant to the total drag Subsequently, the surfaces on which the local pressure highly acts have been modified to produce the streamlined-shape. Based on the surface modification, seven different hull forms have been chosen as candidates for drag reduction. Among the candidates, the semi-sphericalized housing and the streamlined-bow achieved greatest drag reduction comparing with the others. Consequently, the hull form combined with the semi-sphericalized housing and the streamlined-bow gave approximately 17% drag reduction at the design velocity of 3 knots.
Application of IDA Method for Hull Plate Forming by Multi-Point Press Forming
Yoon, Jong-Sung ; Lee, Jang-Hyun ; Ryu, Cheol-Ho ; Hwang, Se-Yun ; Lee, Hwang-Beom ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 75~82
Flame bending has been extensively used in the shipbuilding industry for hull plate forming In flame bending it is difficult to obtain the desired shape because the residual deformation dependson the complex temperature distribution and the thermal plastic strain. Mechanical bending such as reconfigurable press forming multi-point press forming or die-less forming has been found to improve the automation of hull plateforming because it can more accurately control the desired shape than line heating. Multi-point forming is a process in which external forces are used to form metal work-pieces. Therefore it can be a flexible and efficient forming technique. This paper presents an optimal approach to determining the press-stroke for multi-point press forming of curved shapes. An integrated configuration of Finite element analysis (FEA) and spring-back compensation algorithm is developed to calculate the strokes of the multi-point press. Not only spring-back is modeled by elastic plastic shell elements but also an iterative algorithm to compensate the spring-back is applied to adjust the amount of pressing stroke. An iterative displacement adjustment (IDA) method is applied by integration of the FEA procedure and the spring-back compensation work. Shape deviation between the desired surface and deform￡d plate is minimized by the IDA algorithm.
Development of Formulas to Predict Deformations in Plate by Line Heating Method
Lee, Joo-Sung ; Lee, Joung-Ho ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 83~87
Although a great deal of research has been carried out to solve the plate forming problem and to improve the effectiveness and productivity of the plate forming process, no practical way of automating the plate forming process has been proposed yet. Since characteristics of heating machines may vary, it is necessary to investigate the thermal deformation characteristics of the heating machine that will be used in the automation system its characteristics may be modified as new information about thermal deformation by heating becomes available. In this paper, experiments for line heating have been carried out to calculate the formula of predicting thermal deformation due to line heating with varying affecting parameters, and numerical study has been carried out to produce data beyond the range where a line heating test is impractical. Formulas of predicting transverse distortion and shrinkage have been proposed and derived, based on the present experimental and numerical works. This paper also illustrates how the formula has been modified as new experimental data are added.
Thermal-Hydraulic Analysis of Pipeline Transport System for Marine Geological Storage of Carbon Dioxide
Huh, Cheol ; Kang, Seong-Gil ; Hong, Sup ; Choi, Jong-Su ; Baek, Jong-Hwa ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 88~94
The concentration of atmospheric carbon dioxide (CO2), which is one of the major greenhouse gases, continues to rise with the increase in fossil fuel consumption. In order to mitigate global warming the amount of CO2 discharge to the atmosphere must be reduced. Carbon dioxide capture and storage (CCS) technology is now regarded as one of the most promising options. To complete the carbon cycle in a CCS system, a huge amount of captured CO2 from major point sources such as power plantsshould be transported for storage into the marine or ground geological structures. Since 2005, we have developed technologies for marine geological storage of CO2,including possible storage site surveys and basic design of CO2 transport and storage process. In this paper, the design parameters which will be useful to construct on-shore and off-shore CO2 transport systems are deduced and analyzed. To carry out this parametric study, we suggested variations in thedesign parameters such as flow rate, diameter, temperature and pressure, based on a hypothetical scenario. We also studied the fluid flow behavior and thermal characteristics in a pipeline transport system.
Prediction and Control of Welding Deformation for Panel Block Structure
Kim, Sang-Il ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 95~99
The block assembly of ship consists of a certain type of heat processes such as cutting, bending welding residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper proposes a simplified analysis method to predict the welding deformation of panel block structure. For this purpose, a simple prediction model for fillet welding deformations has been derived based on numerical and experimental results through the regression analysis. On the basis of these results, the simplified analysis method has been applied to some examples to show its validity.
A Study on the Prediction and Control of Angular Distortion in Thick Weldments
Kim, Sang-Il ;
Journal of Ocean Engineering and Technology, volume 22, issue 6, 2008, Pages 100~105
The block assembly of ship consists of a series of heat processes such as cutting, bending, welding residual stress relaxation and fairing With the fast development of computers, the thermal elasto-plastic analysis method has become a versatile tool for practical applications in the ship production. If numerical analysis is proved to be an advantageous tool to predict the residual deformation due to various heat processes, the optimum methods which can remove the welding distortion can be presented at each assembly stage, which will result in great progress in improving the accuracy of block assembly. In order to minimize the weld-induced angular distortion in thick weldments, this paper proposes the optimum groove design for various plate thickness as the distortion control method. The validity of this method has been substantiated by a number of numerical simulations and experiments.